Re: [PATCH v7 1/5] block: Don't invalidate pagecache for invalid falloc modes

Darrick J. Wong
2023-05-19T15:17:34Z

On Thu, May 18, 2023 at 03:33:22PM -0700, Sarthak Kukreti wrote:
> Only call truncate_bdev_range() if the fallocate mode is
> supported. This fixes a bug where data in the pagecache
> could be invalidated if the fallocate() was called on the
> block device with an invalid mode.
>
> Fixes: 25f4c41415e5 ("block: implement (some of) fallocate for block devices")
> Cc: stable@vger.kernel.org
> Reported-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>

Thanks for fixing this,

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> block/fops.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/block/fops.c b/block/fops.c
> index d2e6be4e3d1c..4c70fdc546e7 100644
> --- a/block/fops.c
> +++ b/block/fops.c
> @@ -648,24 +648,35 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
>
> filemap_invalidate_lock(inode->i_mapping);
>
> - /* Invalidate the page cache, including dirty pages. */
> - error = truncate_bdev_range(bdev, file->f_mode, start, end);
> - if (error)
> - goto fail;
> -
> + /*
> + * Invalidate the page cache, including dirty pages, for valid
> + * de-allocate mode calls to fallocate().
> + */
> switch (mode) {
> case FALLOC_FL_ZERO_RANGE:
> case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
> + error = truncate_bdev_range(bdev, file->f_mode, start, end);
> + if (error)
> + goto fail;
> +
> error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
> len >> SECTOR_SHIFT, GFP_KERNEL,
> BLKDEV_ZERO_NOUNMAP);
> break;
> case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
> + error = truncate_bdev_range(bdev, file->f_mode, start, end);
> + if (error)
> + goto fail;
> +
> error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
> len >> SECTOR_SHIFT, GFP_KERNEL,
> BLKDEV_ZERO_NOFALLBACK);
> break;
> case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
> + error = truncate_bdev_range(bdev, file->f_mode, start, end);
> + if (error)
> + goto fail;
> +
> error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
> len >> SECTOR_SHIFT, GFP_KERNEL);
> break;
> --
> 2.40.1.698.g37aff9b760-goog
>